LTC4007EUFD-1#PBF Linear Technology, LTC4007EUFD-1#PBF Datasheet - Page 11

• Manufacturer Part Number: LTC4007EUFD-1#PBF
• Description: IC CHARGER BATTERY 4A 24-QFN
• Manufacturer: Linear Technology

Specifications of LTC4007EUFD-1#PBF

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 6 V ~ 28 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-WFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

OPERATIO
gate of the input FET is driven to a voltage sufficient to keep
a low forward voltage drop from drain to source. If the
voltage between DCIN and CLN drops to less than 25mV,
the input FET is turned off slowly. If the voltage between
DCIN and CLN is ever less than – 25mV, then the input FET
is turned off in less than 10µs to prevent significant
reverse current from flowing in the input FET. In this
condition, the ACP pin is driven low and the charger is
disabled.
Battery Charger Controller
The LTC4007-1 charger controller uses a constant off-
time, current mode step-down architecture. During nor-
mal operation, the top MOSFET is turned on each cycle
when the oscillator sets the SR latch and turned off when
the main current comparator I
While the top MOSFET is off, the bottom MOSFET is turned
on until either the inductor current trips the current com-
parator I
oscillator uses the equation:
t
OFF
=
REV
V
V
DCIN
DCIN
or the beginning of the next cycle. The
–
•
U
V
f
OSC
BAT
CMP
resets the SR latch.
5, 6, 7
LTC4007-1: State Diagram
12, 13, 14, 15, 16
SHUTDOWN
SHUTDOWN
CONDITION
MASTER
CHARGE
2
4
11
to set the bottom MOSFET on time. The result is a nearly
constant switching frequency over a wide input/output
voltage range. This activity is diagrammed in Figure 1.
The peak inductor current, at which I
latch, is controlled by the voltage on ITH. ITH is in turn
controlled by several loops, depending upon the situation
at hand. The average current control loop converts the
voltage between CSP and BAT to a representative current.
Error amp CA2 compares this current against the desired
current programmed by R
TGATE
BGATE
INDUCTOR
CURRENT
1
3, 8,
9, 10
ANY
OFF
OFF
ON
ON
3, 17, 18,
19, 20, 21
40071
TBL01
TRIP POINT SET BY ITH VOLTAGE
Figure 1
t
OFF
PROG
at the PROG pin and
LTC4007-1
CMP
resets the SR
11
40071
40071f
F01